Borrelia burgdorferi infection in UK horses.

This study investigates the occurrence and effects of Borrelia burgdorferi, the bacteria causing Lyme disease, in horses in the United Kingdom and identifies that while infection does occur, clinical symptoms are uncommon.

Study Tools and Methods

• The researchers measured the levels of two types of antibodies (IgG and IgM) against Borrelia burgdorferi. These antibodies can signify an active or past infection since when a body is infected by a bacterium or virus, it produces these antibodies to fight the infection.
• This antibody testing was performed on two types of samples from the horses: sera (the clear liquid that can be separated from clotted blood) and synovial fluids (the fluid that is found in the cavities of joints).
• Further, the researchers used a laboratory technique called Western blotting on samples from horses that tested positive for these antibodies (seropositive). This procedure is a sensitive one that is used to detect specific proteins.

Key Findings

• A general trend emerged where areas with a high incidence of human and canine borreliosis (Lyme disease) also showed an increased occurrence in horses – specifically noted were Norfolk and the south coast.
• It was verified that Leptospira infections in horses (another type of bacterial infection) did not skew the results by causing false positives in the Borrelia burgdorferi antibody testing. This is an essential step to validate the specificity of the test being used.

Implications and Conclusions

• Most horses did not show clinical signs of Lyme disease despite testing positive for antibodies against Borrelia burgdorferi. This indicates that while the horses might have been exposed to the bacteria, most did not develop the disease symptoms. This is similar to the disease pattern observed in dogs and humans.
• This research highlights that while the infection may be present in horses in the UK, developing Lyme disease from these infections is rare. Further studies may be needed to understand why this disease manifestation is lower in horses compared to humans and dogs.